Manufacture of electrical heating appliances.



UNITED STATES PATENT CFFICE;

ADOLF VOGT, OF WESTMINSTER, ENGLAND, ASSIGNOR TO ELECTRIC RESIST- ANCE & HEATING COMPANY, LIMITED, OF LONDON, ENGLAND.

MANUFACTURE OF ELECTRICAL HEATING APPLIANCES.

SPECIFICATION forming part of Letters Patent No. 669,130, dated March 5, 1901.

Application filed May 23, 1900. Serial No. 17,757. (No model.)

To all whom it may concern: 400 centigrade. When such reduction of Be it known that I, ADOLF VOGT, engineer, the more or less oxidized metal has been coma citizen of Germany, residing at 82 Victoria pletely effected by this means, (such oxidastreet, Westminster, in the countyof Middletion will mainly occur on the surface of the 55 sex,England, have invented acertain new and particles,) the mass while still surrounded by useful Improved Manufacture of Electrical hydrogen gas is heated to so high a degree that Heating Appliances of High Electrical Resistit becomes fritted or slagged-that is to say, ance Capable of Sustaining I-Iigh Temperamore or less vitrifiedforming a dense, hard tures, (for which Ihave made application for body. The temperature employed should 6o to patent in Great Britain, dated November 7, about equal the welding heat of the metal 1899, No. 22,271,) of which the following is a constituent, but should not exceed this. specification. In the above process special care has to be This invention relates to a manufacture of taken that the metal is kept as free as possielectric heating appliances of high electrical ble from contact With carbon, as otherwise 65 resistance which shall be capable of prod ucthe bodies produced when subject to frequent ing and sustaining very high temperatures use are liable to become of increased resistduring long-continued use and which are ance, the metal becoming brittle and of remainly composed of a mixture of a non-conduced conducting power. ducting substance and a metal conductor. The subjecting the resistance bodies first to 70 As non-conductor there may be used for this a comparatively low temperature in an atmospurpose kaolin, alumina, talc, quartz, and phere of hydrogen and then to a high temthe like, also all very diflicultly reducible or perature while still surrounded by hydrogen fusible metallic oxids, such as aluminium instead of subjecting them at once to a high oxid and the so-called rar eartlfs, the estemperature while surrounded by carbon-pow- 75 sential characteristic of the material emder, as was heretofore done, constitutes the ployed, or of some part thereof, being that essential andimportant feature of the present when heated toahigh degree it shall become invent-ion, inasmuch as the metal employed fritted, slagged, or more or less vitrified, so as being unavoidably more or less oxidized it is to form a hard dense body. The metals emnecessary to effect its complete reduction by 8o ployed as the conducting materialare nickel; means of the hydrogen gas before the noncobalt, Wolfram, and the like. For forming conducting constituent has been made to asthe heating bodies of a mixture of such masume the dense fritted or vitrified condition terials it is indispensably necessary to first by the application of a high heat, as if the reduce them to an exceedingly fine state of still-oxidized particles become reduced, and 35. subdivision and then to mix them intimately consequently shrink in volume,after the nontogether and form the mixture into a paste conducting constituent has assumed the said or dough by the addition of water or other hard condition this can no longer shrink to liquid. From this dough,which can be Worked a corresponding extent,and as a consequence like potters clay, the heating bodies can be the metal particles would not be in such relato molded of any desired configuration or the tive positions in the mass as would enable plastic compound can be pressed in molds, themto afford the requisite conducting power such pressure being only effected in order to for giving the body the exact degree of reinsure perfectly uniform dimensions when sistance requiredthat is to say, the resistthe heating bodies are to be manufactured ance would be too high and unreliable, and 5 45 on a large scale. After molding, the heating consequently the body practically useless.

bodies are dried, and they are then heated in By means of the above-described process, an atmosphere of hydrogen gas, at first only which only relates to the use of metals as the to such a temperature that the more or less conductorin the heating body, the above-menoxidized metal particles shall be completely tioned disadvantages of the existing manufac- 550 reduced. For example, when nickel is used tures of such bodies are entirely obviated and as the metal the temperature would be about an essentially improved product is obtained.

baked are caused to shrink and assume a dense fritted or more or less vitrified condition. By this process alone is it possible to produce electrical heating bodies that shall have and maintain for a long time the desired degree of resistance,and consequently of heating power.

Electrical heating bodies man ufactured according to the above-described invention are particularly applicable with advantage for effecting the preliminary heating of secondclass conductors, also for lighting cigars and pipes, for heating branding-dies, and a variety of similar purposes.

It is not intended to claim generally either the use of hydrogen gas as the red ucing-gas in the manufacture of electrical resistance bodies nor the use of nickel as the metallic constituentof such bodies, as I am aware that these have been proposed separately in the manufacture of glow-lamp filaments and the like, but not in combination and in the manner herein described.

Having thus described the nature of this invention and the best means I know for carrying the same into practical effect, I claim- 1. Process for the manufacture of electrical heating appliances capable of sustaining high temperatures for a long time, which consists in first subjecting a compound composed of a mixture of a finely-divided metal such as nickel and a non-conducting material such as kaolin, or equivalent material, to only such a temperature in a reducing atmosphere as to cause all the oxidized metal particles to be reduced thereby to the metallic state, and then heating the compound to about the welding temperature of the metal, whereby the nonconducting particles of the compound are caused to assume a fritted or more or less vitreous hard, dense condition, the reducing agent employed for this purpose being hydrogen, under careful avoidance of carbon, substantially as and for the purposes described.

2. In the manufacture of electrical heating resistances the process, which consists in compounding a salt of a conductive metal with a refractory non-conductive material having the property of becoming fritted, slagged or more or less vitrified, reducing said salt to a metallic state in a reducing atmosphere, then subjecting the compound to a temperature sufficiently high to frit, slag or vitrify the refractory material, for the purpose set forth.

3. In the manufacture of electrical heating resistances,the process,whichconsists in compounding a salt of a conductive metal with a finely-divided refractory non-conductive material having the property of becoming fritted, sla'gged, or more or less vitrified, forming a plastic body therewith, reducing the aforesaid salt. to a metallic state in an atmosphere of hydrogen, and then subjecting the body to a temperature sufficiently high to frit, slag or more or less vitrify the non-conductive material, for the purpose set forth.

4. As an article of manufacture, an electrical resistance consisting of a fritted ,slagged or more or less vitrified non-conductor and a conductive metal disseminated throughout the same, substantially as set forth.

In testimony whereof I have hereunto set my hand in presence of two subscribing witnesses.

ADOLF VOG'I.

Witnesses EDWARD GARDNER, WALTER J. SKERTEN. 

